Optical touch apparatus having a light guide with scattering particles

ABSTRACT

An optical touch apparatus includes a light source capable of emitting a beam, a light guide unit disposed in a transmission path of the beam, and an optical detector. The light guide unit includes a light guide body having a first surface, a second surface, a third surface, a fourth surface, and a scattering structure disposed on at least one of the second surface, the third surface, and the fourth surface. The beam is capable of entering the light guide body, being scattered to the first surface by the scattering structure, and then being transmitted to a sensing space. The scattering structure includes separated scattering patterns including a resin composition and scattering particles dispersed in the resin composition. The ratio of the weight percentage of the scattering particles to the weight percentage of the resin composition is equal to or greater than 0.1.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan application serial no. 98140208, filed on Nov. 25, 2009. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is related to a touch apparatus, and more particularly, to an optical touch apparatus.

2. Description of Related Art

With the development of optoelectronic technology, a user's requirements may no longer be satisfied by using a mouse to control objects in a computer and a screen. Hence, interfaces more user-friendly than the mouse have been gradually developed. In these user-friendly interfaces, the touch method by using fingers is closest to human experiences in the daily life. In particular, it is easier for elders and children to touch an object with fingers than the mouse. This has been partially proved by the adoption of the touch screen in some automatic teller machines.

In addition, for a conventional laptop, if no mouse is externally connected, a touch pad and a track point next to the keys are usually used to control the cursor. However, controlling the cursor by the touch pad or the track point next to the keys may not be easier than a mouse for normal users. A touch panel disposed on the monitor is able to solve such problem. Because the control method of the touch panel is an intuitive control method, in which the user directly touches the monitor to control the objects. Therefore, when the touch panel is applied to the laptop, even if the operating conditions make the user inconvenient to externally connect the mouse, the user is capable of agilely operating the laptop by the touch panel.

Currently, touch panels are roughly classified into resistive-type, capacitive-type, optical-type, acoustic-wave-type, and electromagnetic-type. Generally, an optical-type touch panel includes a display, a light source, a light guide unit, a detector, and a processor. The light source is disposed next to a display area to generate a beam. The beam passes through the light guide unit and then is detected by the detector. When an object touches the panel, the processor determines a position of a touch point according to a change in light intensity detected by the detectors. In addition, the uniformity of the luminance of the beam passing through the light guide board affects the accuracy in determining the touch point. The more uniform the luminance is, the higher the accuracy is. However, according to prior art, the luminance of the beam passing through the light guide board is non-uniform, so that the accuracy in determining the position of the touch point is also lower.

SUMMARY OF THE INVENTION

The invention provides an optical touch apparatus having higher accuracy in determining a touch point.

Other objects and advantages of the invention may be further comprehended by reading the technical features described in the invention as follows.

One embodiment of the invention provides an optical touch apparatus adapted to a display area. The optical touch apparatus includes at least one light source, at least one light guide unit, and at least one optical detector. The light source is disposed next to the display area and capable of providing a beam. The light guide unit is disposed next to the display area and in a transmission path of the beam. The light guide unit includes a light guide body and a scattering structure. The light guide body has a first surface, a second surface opposite to the first surface, at least one light incident surface connecting the first surface and the second surface, a third surface connecting the light incident surface, the first surface, and the second surface, and a fourth surface opposite to the third surface and connecting the light incident surface, the first surface, and the second surface. The beam is capable of entering the light guide body through the light incident surface and is capable of being transmitted from the first surface to a sensing space in front of the display area. The scattering structure is disposed on at least one of the second surface, the third surface, and the fourth surface, so that the beam is scattered to the first surface. The scattering structure has a plurality of scattering patterns separated from each other, and each of the scattering patterns includes a resin composition and a plurality of scattering particles. The scattering particles are dispersed in the resin composition, and a ratio of a weight percentage of the scattering particles to a weight percentage of the resin composition is equal to or greater than 0.1. The optical detector is disposed next to the display area and capable of detect a change in light intensity of the beam in the sensing space.

Due to the above, the embodiments of the invention may have at least one of the following advantages. In each of the scattering patterns of the optical touch apparatus according to the embodiments of the invention, the ratio of the weight percentage of the scattering particles to the weight percentage of the resin composition is equal to or greater than 0.1, so that the scattering particles in the scattering patterns are beneficial to adjusting the emitted light shape of the beam passing through the scattering patterns. Hence effects of uniformed emitted luminance of the light guide unit are achieved, thereby enhancing the accuracy in determining the touch point by the optical touch apparatus.

Other objectives, features and advantages of the invention will be further understood from the further technological features disclosed by the embodiments of the invention wherein there are shown and described preferred embodiments of this invention, simply by way of illustration of modes best suited to carry out the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1A is a structural schematic diagram of an optical touch display apparatus according to an embodiment of the invention.

FIG. 1B is a schematic cross-sectional view of an optical touch apparatus in FIG. 1A along line I-I.

FIG. 2A is a three-dimensional view of a light guide unit and a light source in FIG. 1A.

FIG. 2B is a three-dimensional view of a light guide body and a scattering structure in FIG. 2A.

FIG. 2C is a schematic cross-sectional view of the light guide unit in FIG. 2A along line II-II.

FIG. 2D is a three-dimensional view of the light guide body and scattering structure of the light guide unit in FIG. 1A.

FIG. 3A is a light intensity distribution diagram of a first surface of the light guide unit detected by an optical detector in FIG. 1A.

FIG. 3B is a light intensity distribution diagram of the first surface of the light guide unit detected by the optical detector when the scattering structure is formed by a transparent ink layer.

FIG. 4A is a light intensity distribution curve diagram of a light beam passing through the scattering pattern and emitted from a first surface of the light guide body according to an embodiment of the invention, in which there are different ratios of scattering particles to a resin composition.

FIG. 4B is a light intensity distribution curve diagram of the light beam passing through the scattering pattern having scattering particles with different particles sizes and emitted from the first surface of the light guide body according to an embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” etc., is used with reference to the orientation of the Figure(s) being described. The components of the invention can be positioned in a number of different orientations. As such, the directional terminology is used for purposes of illustration and is in no way limiting. On the other hand, the drawings are only schematic and the sizes of components may be exaggerated for clarity. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the invention. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. Similarly, the terms “facing,” “faces” and variations thereof herein are used broadly and encompass direct and indirect facing, and “adjacent to” and variations thereof herein are used broadly and encompass directly and indirectly “adjacent to”. Therefore, the description of “A” component facing “B” component herein may contain the situations that “A” component directly faces “B” component or one or more additional components are between “A” component and “B” component. Also, the description of “A” component “adjacent to” “B” component herein may contain the situations that “A” component is directly “adjacent to” “B” component or one or more additional components are between “A” component and “B” component. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive.

Referring to FIGS. 1A, 1B, and 2A to 2C, an optical touch display apparatus 40 of an embodiment of the invention includes a display 50 and an optical touch apparatus 100. According to the embodiment, the display 50 includes a display area 52 and an outer frame 54 surrounding the display area 52. The optical touch apparatus 100 may be disposed on the outer frame 54 or be integrated as a part of the outer frame 54. The display 50 is, for example, a liquid crystal display (LCD), a plasma display panel (PDP), an organic light emitting diode (OLED) display, a cathode ray tube (CRT) display, a rear projection display, or another kind of display, while the display area 52 is a surface for displaying frames to a user. According to other embodiments, the display area 52 may also be a display region on a projection screen, meaning that the optical touch apparatus 100 is capable of being used with a projection apparatus and disposed next to the display region on the projection screen.

The optical touch apparatus 100 includes at least one light source 110 (four light sources 110 a, 110 b, 110 c, and 110 d are exemplarily shown in FIG. 1), at least one light guide unit 130 (three light guide units 130 a, 130 b, and 130 c are exemplarily shown in FIG. 1), and at least one optical detector 120 (two optical detectors 120 a and 120 b are exemplarily shown in FIG. 1). The light source 110 is disposed next to the display area 52 and is capable of emitting a beam 112. The light guide unit 130 is disposed next to the display area 52 and is disposed in the transmission path of the beam 112. Specifically, the light sources 110 a, 110 b, 110 c, and 110 d respectively emit beams 112 a, 112 b, 112 c, and 112 d, the light guide unit 130 a is disposed in the transmission path of the beam 112 a, the light guide unit 130 b is disposed in the transmission paths of the beams 112 b and 112 c, and the light guide unit 130 c is disposed in the transmission path of the beam 112 d.

According to the embodiment, the light source 110 includes an invisible light emitting diode capable of emitting an invisible beam. For example, the light source 110 is an infrared light emitting diode, and each of the beams 112 a, 112 b, 112 c, and 112 d is an infrared beam.

The optical detectors 120 a and 120 b are disposed next to the display area 52. Each of the optical detectors 120 a and 120 b is, for example, a complementary metal-oxide-semiconductor (CMOS) sensor, a charge coupled device (CCD) sensor, a photomultiplier (PMT), or another type of suitable image sensor.

The light guide unit 130 includes a light guide body 131 and a scattering structure 150.

The light guide body 131 has a first surface P1, a second surface P2 opposite to the first surface P1, and at least one light incident surface P0 connecting the first surface P1 and the second surface P2. The beam 112 is capable of entering the light guide body 131 through the light incident surface P0, and is capable of being transmitted from the first surface P1 to a sensing space S (the space surrounded by the broken lines shown in FIG. 1A and FIG. 1B) in front of the display area 52.

According to the embodiment, the light guide body 131 further includes a third surface P3 and a fourth surface P4. The third surface P3 is connected to the light incident surface P0, the first surface P1, and the second surface P2. The fourth surface P4 is opposite to the third surface P3 and is connected to the light incident surface P0, the first surface P1, and the second surface P2. According to the embodiment, the light guide unit 130 further includes a reflector 133 disposed on at least one of the second surface P2, the third surface P3, and the fourth surface P4. Specifically, the reflector 133 is, for example, a reflecting sheet disposed on the second surface P2, the third surface P3, and the fourth surface P4.

According to the embodiment, the scattering structure 150 is, for example but not limited to, a Lambertian scattering structure and disposed on the second surface P2 of the light guide body 131. According to other embodiments, the scattering structure 150 may also be disposed on at least one of the second surface P2, the third surface P3, and the fourth surface P4 of the light guide body 131, so that the beam 112 is scattered to the first surface P1, and the root mean square value D of the differences between the light intensity of the normalized light intensity distribution curve of the beam 112 emitted from the first surface P1 at each light emission angle and the light intensity of a Lambertian normalized light intensity distribution curve at the same angle is equal to or less than 0.2. Specifically, the normalized light intensity distribution curve of the light beam 112 emitted from the first surface P1 may be represented by I(θ), meaning that the light intensity I is a function of the light emission angle θ. The range of the light emission angle θ is from −90 to +90 degrees, wherein the direction corresponding to 0 degree is defined as the light emission direction (i.e. the light emission direction D1 if the light guide unit 130 b is used as an example) perpendicular to the first surface P1; the positive direction of the light emission angle θ is the clockwise direction on the figure, and the negative direction of the light emission angle θ is the counter-clockwise direction on the figure. In addition, the Lambertian normalized light intensity distribution curve may be represented by L(θ), wherein L(θ)=cos θ, and the range of 0 is from −90 to +90 degrees. By using the Lambertian scattering structure according to the embodiment, the normalized light intensity distribution of the beam 112 emitted from the first surface P1 complies with the following equation.

Root mean square value of the differences between the light intensity

$D = {\sqrt{\frac{\sum\left( {{I(\theta)} - {L(\theta)}} \right)^{2}}{N}} \leq 0.2}$

In other words, the light intensity distribution of the beam 112 emitted from the first surface P1 is similar to the Lambertian distribution, so that there is uniform luminance on the first surface P1. According to the embodiment, the above root mean square value D is, for example, 0.063106. However, according to other embodiments, the above root mean square value may be 0.075269, 0.121543, or another value equal to or smaller than 0.2.

According to the embodiment, the light guide units 130 a and 130 b are respectively disposed at two adjacent sides of the display area 52, the light guide units 130 b and 130 c are respectively disposed at two adjacent sides of the display area 52, and the light guide units 130 a and 130 c are respectively disposed at two opposite sides of the display area 52. The first surface P1 of the light guide unit 130 may face the sensing space S. The first surface P1 of the light guide unit 130 a and the first surface P1 of the light guide unit 130 b are in the detection range of the optical detector 120 b, and the first surface P1 of the light guide unit 130 b and the first surface P1 of the light guide unit 130 c are in the detection range of the optical detector 120 a. The optical detector 120 is used to detect the change in the light intensity of the beam 112 in the sensing space S. According to the embodiment, the optical touch apparatus 100 further includes a processing unit 140 electrically connected to the optical detector 120 (i.e. electrically connected to the optical detectors 120 a and 120 b). The processing unit 140 determines the position of the touch object relative to the display area 52 according to the change in light intensity when a touch object 60 enters the sensing space S.

Specially, when the touch object 60 approaches or touches the display area 52, the touch object 60 blocks the beam 112 emitted from the first surface P1 of each light guide unit 130 a, 130 b, and 130 c and entering the optical detectors 120 a and 120 b, so that dark spots on the images are sensed by the optical detectors 120 a and 120 b. By analyzing the positions of the dark spots, the processing unit 140 is able to calculating the position of the touch object 60 relative to the display area 52, thereby achieving a touch effect. The touch object 60 is, for example, the finger of the user, a tip of a stylus, or another suitable object. In addition, the processing unit 140 is, for example, a digital signal processor (DSP) or other kind of suitable processing circuit. The processing unit 140 may be electrically connected to a processor of an operating platform, such as a computer, cell phone, personal digital assistant (PDA), digital camera, or to processors of other kind of electronic device, and the processor of the operating platform is capable of converting a signal of the position of the touch object 60 relative to the display area 52 into various kinds of control functions. According to other embodiments, the position of the touch object 60 relative to the display area 52 may be calculated by the processor of the operating platform instead of by the processing unit 140.

According to the embodiment, the scattering structure 150 includes a plurality of scattering patterns 152 which are separated from each other. The scattering patterns 152 are capable of making the beam 112 emitted from the first surface P1 have a light intensity distribution similar to the Lambertian intensity distribution. The scattering patterns 152 are arranged in a direction substantially perpendicular to the light incident surface P0 (the normal direction of the surface). In addition, according to the embodiment, the number density of the scattering patterns 152 at a region close to the light source 110 is less than the number density of the scattering patterns 152 at a region away from the light source 110. For example, the number density of the scattering patterns 152 increases along the direction away from the light source 110. Moreover, the light guide unit 130 b has two light incident surfaces P0 opposite to each other, and the two light incident surfaces P0 are the light incident surfaces 132 b and 134 b. The light sources 110 b and 110 c are respectively disposed next to the two light incident surfaces 132 b and 134 b opposite to each other, and the number density of the scattering patterns 152 at a region close to one of the light incident surfaces 132 b and 134 b is less than the number density of the scattering patterns 152 at a region in the middle between the light incident surfaces 132 b and 134 b. For example, the number density of the scattering patterns 152 increases from two ends of the light guide unit 130 b towards the middle.

In addition, the light guide body 131 of the light guide unit 130 a (referring to FIG. 2D) has one light incident surface P0, and the light incident surface P0 is a light incident surface 132 a. The number density of the scattering patterns 152 increases from the end close the light incident surface 132 a to the end away from the light incident surface 132 a. The light guide unit 130 c and the scattering patterns 152 on the light guide unit 130 c are similar to the light guide unit 130 a and the scattering patterns 152 on the light guide unit 130 a, while the positions of the first surface P1 and the second surface P2 of the light guide unit 130 c are opposite from the positions of the first surface P1 and the second surface P2 of the light guide unit 130 a.

Since the optical touch apparatus 100 according to the embodiment adopts the Lambertian scattering structure (which is the scattering structure 150), the light intensity distribution of the beam 112 emitted from the first surface P1 is similar to the Lambertian distribution, and uniform luminance is on the first surface P1. Therefore, when the touch object 60 does not enter the sensing space S, the optical detector 120 may detect uniform luminance at each sensing angle. Hence, when the touch object 60 enters the sensing space S, the processing unit 140 is capable of accurately calculating the position of the touch object 60 relative to the display area 52 by analyzing data of the light intensity distribution transmitted from the optical detector 120, so that the problem of misjudgment of the position of the touch object 60 caused by non-uniform luminance on the first surface P1 is improved.

According to the embodiment, each of the scattering patterns 152 includes a resin composition 154 and a plurality of scattering particles 156. The resin composition 154 is, for example, a transparent ink layer but not limited to it. The resin composition 154 is disposed on the second surface P2. According to other embodiments, the resin composition 154 may also be disposed on at least one of the second surface P2, the third surface P3, and the fourth surface P4. The scattering particles 156 are dispersed in the resin composition 154. Through cooperation of the resin composition 154 and the scattering particles 156, the Lambertian scattering structure is formed. In the embodiments of the invention, the Lambertian scattering structure is not limited to being formed by the resin composition and the scattering particles. According to other embodiments, the Lambertian scattering structure may also be any structure capable of making the beam 112 emitted from the first surface P1 have a light intensity distribution similar to the Lambertian intensity distribution.

Referring to both FIGS. 3A and 3B, from left to right, the angular range of detection by the optical detector 120 a is from the light incident surface 132 b of the light guide unit 130 b to the light incident surface 134 b of the light guide unit 130 b. Referring to FIG. 3B, when the scattering structure is formed by the transparent ink layer and does not contains any scattering particles, the light emission angle θ of the beam 112 emitted from the first surface P1 and by the light source 110 b deviates towards the positive direction, and the light emission angle θ of the beam 112 emitted from the first surface P1 by the light source 110 c deviates towards the negative direction. Hence, the beam 112 emitted by the light source 110 c directly irradiates the optical detector 120 a and causes a stronger light intensity, and the beam emitted by the light source 110 b deviates from the optical detector 120 a and causes a weaker light intensity. Hence, the light intensity distribution in FIG. 3B is non-uniform and is higher at the right side of FIG. 3B, thereby easily causing misjudgment of a position of a touch point. Referring to FIG. 3A, since the optical touch apparatus 100 according to the embodiment adopts the transparent ink layer with the scattering particles 156, the light intensity distribution of the beam 112 emitted from the first surface P1 of the light guide unit 130 b is similar to the Lambertian intensity distribution. Hence, the optical detector 120 a is capable of detecting the uniform light intensity distribution as shown in FIG. 3A, thereby effectively lowering the misjudgment rate of the position of the touch point by the optical touch apparatus 100 and the optical touch display apparatus 40 according to the embodiment. In other words, the accuracy in determining the position of the touch point by the optical touch apparatus 100 and the optical touch display apparatus 40 is enhanced.

In order to make clear the characteristics of the invention, the following illustrates the scattering structure 150 in detail. The scattering structure 150 has the plurality of scattering patterns 152 separated from each other, and the scattering patterns 152 are disposed on at least one of the second surface P2, the third surface P3, and the fourth surface P4 opposite to the light emitting surface in the light guide body 131. In particular, a designer may adjust the composition ratio of the resin composition 154 to the plurality of scattering particles 156 in the scattering patterns 152 to adjust the emitted light shape of the beam 112, so that the beam 112 achieves a uniform effect. In application, by adjusting a suitable ratio of the resin composition 154 to the plurality of scattering particles 156 in the scattering patterns 152, the normalized light intensity distribution curve of the beam 112 achieves an effect similar to an effect of the Lambertian normalized light intensity distribution curve.

In detail, each of the scattering patterns 152 includes the resin composition 154 and the plurality of scattering particles 156, and the scattering particles 156 are dispersed in the resin composition 154. The contents of the scattering particles 156 and the resin composition 154 in the scattering patterns are calculated as weight percentages. In other words, when the ratio of the weight percentage of the scattering particles 156 in the scattering patterns 152 to the weight percentage of the resin composition 154 in the scattering patterns 152 is equal to or greater than 0.1, the scattering patterns 152 may be sufficiently used to adjust the light shape of the beam 112. As shown in FIGS. 3A and 3B described above, the beam 112 emitted from the light guide body 131 are more uniform when the content of the scattering particles 156 in the scattering patterns 152 comply with the above relationship, so that the optical detector 120 effectively detects whether there is a change in light intensity caused by touching in the sensing space S, thereby preventing misjudgment of touching.

In addition, according to the embodiment, since the content of the scattering particles 156 in the scattering patterns 152 is less than the content of the resin composition 154 in the scattering patterns 152, such as the ratio of the scattering particles 156 to the resin composition 154 being 0.1, in each of the scattering patterns 152 as shown in FIGS. 2B to 2D, the resin composition 154 may be viewed as a continuous phase, the scattering particles 156 may be viewed as a dispersed phase dispersed in the continuous phase, and the scattering particles 156 are, for example, embedded in the resin composition 154.

In practice application, by adjusting the scattering particles 156 and the composition ratio of the plurality of scattering particles 156 in the scattering pattern 152, the light shape of the beam 112 passing through the scattering patterns 152 are more suitable for product requirements. For example, in one kind of application, if the light shape of beam emitted from the light guide body 131 is to comply with the Lambertian light shape, the ratio of the scattering particles 156 to the resin composition 154 may be appropriately increased. Specifically, the ratio of the scattering particles 156 to the resin composition 154 is preferably smaller than or equal to 1.5. The contents of the scattering particles 156 and the resin composition 154 are calculated in weight percentages. Moreover, from a view of light usage efficiency, when the contents of the scattering particles 156 and the resin composition 154 in the scattering patterns 152 are calculated in weight percentages, the ratio of the scattering particles 156 to the resin composition 154 is preferably greater than or equal to 0.5 and smaller than or equal to 1.5.

In other words, when the content of the scattering particles 156 in the scattering patterns 152 is greater than the content of the resin composition 154 in the scattering patterns 152, such as the ratio of the scattering particles 156 to the resin composition 154 is 1.5, and the scattering particles may protrude from the surface of the resin composition, so that the surface of the resin composition is slightly uneven and formed as a tiny concave/convex structure surface. The invention, however, does not limit the manner in which the scattering particles are dispersed in the resin composition.

Referring to FIG. 4A, the light shapes of the beam 112 are shown under the conditions that the ratio of the scattering particles 156 to the resin composition 154 is 0.1, 1, and 1.5. As shown in FIG. 4A, when the ratio of the scattering particles 156 and the resin composition 154 changes, the light intensity distribution curve diagram of the beam 112 changes accordingly. In detail, when the weight percentage of the scattering particles 156 in the scattering patterns 152 to the weight percentage of the resin composition 154 in the scattering patterns 152 is equal to or greater than 0.1, the light shape of the emitted beam 112 is substantially changed. Moreover, as shown in FIG. 4A, when the ratio of the weight percentage of the scattering particles 156 in the scattering patterns 152 to the weight percentage of the resin composition 154 in the scattering patterns 152 is 1 or 1.5, the light shape of the beam 112 passing through the scattering patterns 152 is similar to the shape of Lambertian light.

It should be noted that, the ratio of the scattering particles 156 to the resin composition 154 in the scattering patterns 152 is not specifically limited; as long as the scattering particles 156 added into the resin composition 154 are sufficient, effects of adjusting the emitted light shape of the beam 112 are achieved. In other words, the scattering patterns 152 are capable of substantially adjusting the emitted beam 112 to have a predetermined light shape when the ratio of the weight percentage of the scattering particles 156 in the scattering patterns 152 to the weight percentage of the resin composition 154 in the scattering patterns 152 is equal to or greater than 0.1. For example, as shown in FIG. 4A, in an application wherein the predetermined light shape is the Lambetian light shape, the ratio of the scattering particles 156 to the resin composition 154 in the scattering patterns may be adjusted to substantially 1 or 1.5, so that the emitted beam 112 is adjusted to have the predetermined Lambertian light form. Hence, in the invention, the ratio of the scattering particles 156 to the resin composition 154 in the scattering patterns 152 is not limited to a specific value, but is suitably adjusted according to predetermined requirements on the light shape of the emitted beam.

In addition, for the same light guide body 131, the invention does not limit that the composition ratio of the scattering particles 156 to the resin composition 154 in the scattering patterns 152 of the same light guide body 131 is the same. In detail, for the same light guide body 131, in the scattering patterns 152 located at different positions, the ratio of the scattering particles 156 to the resin composition 154 in the scattering patterns 152 may be adjusted according to the positions of the scattering patterns 152 relative to the optical detectors 120, the number of the optical detectors 120, and the number of the light guide bodies 131 in the light guide unit 130. In other words, each ratio of the scattering particles 156 to the resin composition 154 in the plurality of scattering patterns 152 on the same light guide body 131 may be substantially different from each other. Alternatively, considering the obtainment of raw materials, mass productivity, and the cost of manufacturing, slight variation between each ratio of the scattering particles 156 to the resin composition 154 in the scattering patterns 152 is allowable for the scattering patterns 152 on the same light guide body, so that each ratio of the scattering particles 156 to the resin composition 154 in the scattering patterns 152 may be substantially different from each other.

Based on the above concept, a designer may adjust the compositions of the scattering patterns 152 on different positions of each of the light guide bodies 131 according to the size of the optical touch apparatus, the characteristics (such as the refractive index) of the light guide unit 130, and the relative positions of the light guide unit 130 and the optical detector 120, so that the beam 112 emitted from the light guide body may have uniform effects. Hence, the detection sensitivity and the accuracy in determining the touch point by the optical detector 120 are enhanced, thereby preventing the optical touch apparatus from performing unwanted functions.

The designer may further fine tune the directivity of the beam 112 in an auxiliary manner by adjusting the particle size of the scattering particles when the ratio of the scattering particles 156 to the resin composition 154 in the scattering patterns 152 is equal to or greater than 0.1. Details are described below with reference to FIG. 4B. The particle size of the scattering particles 156 is not specifically limited. In detail, according to the embodiment, the particle size of the scattering particles 156 is substantially in the range from 1 μm to 30 μm.

Referring to FIG. 4B, the light shapes of the emitted beam are shown when the particle size of the scattering particles is 1 μm, 15 μm, and 30 μm. As shown in FIG. 4B, when the particle size of the scattering particles is 1 μm, the light intensity is stronger when the light emission angle is 0 degree. In other words, the emitted beam has higher optical directivity. On the other hand, when the particle size of the scattering particles is 15 μm, compared with the light intensity distribution when the particle size is 1 μm, the light intensity distribution is more uniform when the particle size is 15 μm. Still referring to FIG. 4B, when the particles size of the scattering particles is 30 μm, the light intensity distribution of the beam passing through the scattering patterns is further uniformed.

In other words, when the particle size of the scattering particles 156 is smaller, the optical directivity of the beam 112 passing through the scattering pattern 152 is enhanced; when the size of the scattering particles 156 is close to the wavelengths of visible light, there tends to be slight loss in optical energy, and the light usage efficiency is lowered. On the other hand, when the particles size of the scattering particles 156 is larger, the light usage efficiency of the beam 112 passing through the scattering patterns 152 is enhanced. According to the embodiment, the particles size of the scattering particles 156 is substantially equal to 2 μm, so that the optical directivity and light usage efficiency of the beam 112 passing through the scattering patterns 152 are enhanced.

On the basis of adjusting the emitted light shape of the beam 112 by the scattering patterns 152, by considering other design requirements, the refractive index of the scattering patterns 152 may be further adjusted according to the ratio of the scattering particles 156 to the resin composition 154, the refractive index of the scattering particles 156, and the refractive index of the resin composition 154, so that the light usage efficiency of the beam is further enhanced when the emitted light shape is changed. According to the embodiment, the refractive index of the light guide body 131 is, for example, 1.49. In order to enhance the light usage efficiency, in the scattering patterns 152 arranged on the second surface P2, the refractive index of the resin composition 154 is in the range from 1.4 to 1.55, and the refractive index of the scattering particles 156 is in the range from 1.4 to 1.7.

In terms of manufacturing, the above scattering structure 150 may be manufactured by print fabrication. In further detail, the resin composition 154, the scattering particles 156, and a solvent may be pre-mixed to form a scattering material. Next, the scattering material is, for example, sprayed on the light guide body 131 by a printing process. In addition, a curing process is used for removing the solvent to cure the scattering material sprayed on the light guide body 131, and the scattering structure 150 is formed by the plurality of scattering patterns 152 separated from each other. The curing process is, for example, an ultraviolet light curing process or a baking process. Hence, according to the actual printing process, a solvent with a suitable material and viscosity may be selected. For example, according to the embodiment, the solvent is a composition including 90% 3,5,5-trimethyl-2-cyclohexene-1-one and 10% 4-methyl-3-penten-2-one.

The following further describes the resin composition 154 and the scattering particles 156 in the scattering patterns 152.

The resin composition: in terms of light usage efficiency, according to an embodiment, a material having high optical transmittance in the visible light range may be selected as the resin composition. For example, the optical transmittance of the resin composition in the visible light range is equal to or greater than 90%, and the resin composition in the scattering patterns is, for example, the transparent ink layer. Specifically, the resin composition is formed by a composition including poly methylmethacrylate resin. According to the embodiment, the constituents for forming the resin composition further include an aromatic hydrocarbon compound, a dibasic ester, cyclohexanone, and silicon dioxide.

In terms of the fact that the resin composition has superb optical transmittance and better light usage efficiency, the contents of each compound in the constituents of the resin composition comply with the following relationships: the content of the poly methylmethacrylate resin is, for example, 20-30 wt %, the content of the aromatic hydrocarbon compound is 20-30 wt %, the content of the dibasic ester is 20-30 wt %, the content of the cyclohexanone is 10-20 wt %, and the content of the silicon dioxide in the resin composition is equal to or less than 10 wt %.

The so called scattering particles are particles capable of making incident light beams have different emission directions. The particle size of the scattering particles is, for example, 1 μm to 30 μm, and the selection of the particle size and considerations for the refractive index are illustrated above and hence not repeated described. Specifically, the scattering particles may include, but are limited to, one of titanium dioxide, silicon dioxide, and poly methylmethacrylate resin, or any combination thereof. According to other embodiments, other scattering particles may be selected.

It should be noted that the scattering patterns 152 formed by mixing the resin composition and the scattering particles 156 complying with the above relationships have effects of sufficiently changing the emitted light shape and have superb light usage efficiency, so that the light guide unit 130 utilizing the scattering patterns 152 has effects of the uniform light intensity distribution. Therefore, compared with a conventional optical touch apparatus, the optical touch apparatus of the invention utilizes the scattering patterns 152 having the resin composition 154 and the scattering particles 156, and the resin composition 154 and the scattering particles 156 comply with specific relationships, so that light uniformity of the beam passing through the light guide unit 130 and been emitted into the sensing space is enhanced, thereby enhancing the accuracy in determining the touch point by the optical touch apparatus.

In summary, the embodiments of the invention have at least one of the following advantages. By adjusting the ratio of the scattering particles to the resin composition in the scattering patterns, the light shape of the beam passing through the light guide body is sufficiently adjusted, so that the overall emitted light intensity (luminance) of the light guide body is uniform, thereby enhancing the accuracy in determining the touch point by the optical touch apparatus.

The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form or to exemplary embodiments disclosed. Accordingly, the foregoing description should be regarded as illustrative rather than restrictive. Obviously, many modifications and variations will be apparent to practitioners skilled in this art. The embodiments are chosen and described in order to best explain the principles of the invention and its best mode practical application, thereby to enable persons skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use or implementation contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated. Therefore, the term “the invention”, “the present invention” or the like does not necessarily limit the claim scope to a specific embodiment, and the reference to particularly preferred exemplary embodiments of the invention does not imply a limitation on the invention, and no such limitation is to be inferred. The invention is limited only by the spirit and scope of the appended claims. The abstract of the disclosure is provided to comply with the rules requiring an abstract, which will allow a searcher to quickly ascertain the subject matter of the technical disclosure of any patent issued from this disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Any advantages and benefits described may not apply to all embodiments of the invention. It should be appreciated that variations may be made in the embodiments described by persons skilled in the art without departing from the scope of the invention as defined by the following claims. Moreover, no element and component in the present disclosure is intended to be dedicated to the public regardless of whether the element or component is explicitly recited in the following claims. 

What is claimed is:
 1. An optical touch apparatus, adapted to a display area, the optical touch apparatus comprising: at least one light source, disposed next to the display area and capable of providing a beam; at least one light guide unit, disposed next to the display area and in a transmission path of the beam, the light guide unit comprising: a light guide body, having a first surface, a second surface opposite to the first surface, at least one light incident surface connecting the first surface and the second surface, a third surface connecting the light incident surface, the first surface, and the second surface, and a fourth surface opposite to the third surface and connecting the light incident surface, the first surface, and the second surface, wherein the beam is capable of entering the light guide body through the light incident surface and is capable of being transmitted from the first surface to a sensing space in front of the display area; and a scattering structure, disposed on at least one of the second surface, the third surface, and the fourth surface, so that the beam is scattered to the first surface, wherein the scattering structure has a plurality of scattering patterns separated from each other, each of the scattering patterns comprising a resin composition and a plurality of scattering particles, wherein the scattering particles are dispersed in the resin composition, and a ratio of a weight percentage of the scattering particles to a weight percentage of the resin composition is substantially equal to or greater than 0.1; and at least one optical detector, disposed next to the display area and capable of detecting a change in light intensity of the beam in the sensing space.
 2. The optical touch apparatus of claim 1, wherein in each of the scattering patterns, the ratio of the weight percentage of the scattering particles to the weight percentage of the resin composition is substantially equal to or less than 1.5.
 3. The optical touch apparatus of claim 1, wherein in each of the scattering patterns, the ratio of the weight percentage of the scattering particles to the weight percentage of the resin composition is substantially from 0.5 to 1.5.
 4. The optical touch apparatus of claim 1, wherein the resin composition is a transparent ink layer, and a light transmittance rate of the resin composition is equal to or greater than 90%.
 5. The optical touch apparatus of claim 1, wherein the resin composition comprises poly methylmethacrylate resin, and a weight percentage of the poly methylmethacrylate resin is substantially 20-30 wt %.
 6. The optical touch apparatus of claim 5, wherein the resin composition further comprises an aromatic hydrocarbon compound, and a weight percentage of the aromatic hydrocarbon compound is substantially 20-30 wt %.
 7. The optical touch apparatus of claim 5, wherein the resin composition further comprises a dibasic ester, and a weight percentage of the dibasic ester is substantially 20-30 wt %.
 8. The optical touch apparatus of claim 5, wherein the resin composition further comprises cyclohexanone and silicon dioxide.
 9. The optical touch apparatus of claim 1, wherein a refractive rate of the resin composition is substantially from 1.4 to 1.55.
 10. The optical touch apparatus of claim 1, wherein a particle size of the scattering particles is substantially from 1 μm to 30 μm.
 11. The optical touch apparatus of claim 1, wherein the scattering particles comprise one of titanium dioxide, silicon dioxide, and poly methylmethacrylate resin, or a combination thereof.
 12. The optical touch apparatus of claim 1, wherein a refractive rate of the scattering particles is substantially from 1.4 to 1.7.
 13. The optical touch apparatus of claim 1, wherein each of the scattering patterns is capable of changing the light shape of the beam emitted from the first surface, such that the light shape of the beam emitted from the first surface is changed with the ratio of the scattering particles to the resin composition.
 14. The optical touch apparatus of claim 1, wherein the ratios of the scattering particles to the resin compositions of the plurality of scattering patterns in the same light guide body are substantially different from each other.
 15. The optical touch apparatus of claim 1, wherein a number density of the scattering patterns at a region close to the light source is less than a number density of the scattering patterns at a region away from the light source.
 16. The optical touch apparatus of claim 1, wherein the scattering patterns are arranged in a direction substantially perpendicular to the light incident surface.
 17. The optical touch apparatus of claim 1, wherein the at least one light guide unit is three light guide units, the at least one light source is four light sources, a first light guide unit and a second light guide unit of the three light guide units are respectively disposed at two adjacent sides of the display area, the second light guide unit and a third light guide unit of the three light guide units are respectively disposed at two adjacent sides of the display area, and the first light guide unit and the third light guide unit are respectively disposed at two opposite sides of the display area, the first light guide unit is disposed in a transmission path of a beam emitted by a first light source of the four light sources, the second light guide unit is disposed in a transmission path of a beam emitted by a second light source and in a transmission path of a beam emitted by a third light source of the four light sources, and the third light guide unit is disposed in a transmission path of a beam emitted by a fourth light source of the four light sources.
 18. The optical touch apparatus of claim 17, wherein the at least one light incident surface of the light guide body of the second light guide unit are two light incident surfaces opposite to each other, the second light source and the third light source are respectively disposed next to the two light incident surfaces opposite to each other, and a number density of the scattering patterns at a region close to the light incident surface is less than a number density of the scattering patterns at a region in a middle of the light incident surface.
 19. The optical touch apparatus of claim 17, wherein the first surfaces of the light guide units face the sensing space, the at least one optical detector is two optical detectors, a first surface of the first light guide unit and a first surface of the second light guide unit are in a detection range of one of the two optical detectors, and the first surface of the second light guide unit and a first surface of the third light guide unit are in a detection range of the other of the two optical detectors. 